Moldless Printing of Silicone Lenses with Embedded Nanostructured Optical Filters

Abstract

Optical lenses are among the oldest technological innovations (3000 years ago) and they have enabled a multitude of applications in healthcare and in our daily lives. The primary function of optical lenses has changed little over time; they serve mainly as a light-collection (e.g. reflected, transmitted, diffracted) element, and the wavelength and/or intensity of the collected light is usually manipulated by coupling with various external optical filter elements or coatings. This generally results in losses associated with multiple interfacial reflections, and increases the complexity of design and construction.In this work we introduce a change in this paradigm, by integrating both light-shaping and image magnification into a single lens element using a moldless procedure that takes advantage of the physical and optical properties of mesoporous silicon (PSi) photonic crystal nanostructures. Casting of a liquid poly(dimethyl) siloxane (PDMS) pre-polymer solution onto a PSi film generates a droplet with contact angle that is readily controlled by the silicon nanostructure, and adhesion of the cured polymer to the PSi photonic crystal allows preparation of lightweight (10 mg) freestanding lenses (4.7 mm focal length) with an embedded optical component (e.g. optical rugate filter, resonant cavity, distributed Bragg reflector). Our fabrication process shows excellent reliability (yield 95%) and low cost and we expect our lens to have implications in a wide range of applications. As a proof-of-concept, using a single monolithic lens/filter element we demonstrate: fluorescence imaging of isolated human cancer cells with rejection of the blue excitation light, through a lens that is self-adhered to a commercial smartphone; shaping the emission spectrum of

Nanoscale Photoluminescence Manipulation in Monolithic Porous Silicon Oxide Microcavity Coated with Rhodamine‐Labeled Polyelectrolyte via Electrostatic Nanoassembling

“…Thanks to its versatile, robust, and high‐yield modulation of refractive index and unique nano/mesoporous structure, [ 9,10 ] PSi permits facile fabrication of photonic devices, in particular of microcavities (MCs), and easy introduction of guest emitters. Recently, oxidized porous silicon (PSiO 2 ) has been employed for the fabrication of a number of advanced photonic devices, such as 3D poly(dimethylsiloxane) (PDMS) lenses incorporating 1D photonic crystal components, [ 11 ] and 2D/3D gradient refractive index optical elements. [ 4,12 ] Further, infiltration of PSi with a number of nanomaterials has been carried out to take advantage of the peculiar properties of luminescent guest materials when confined within silicon‐based photonic structures with characteristic length down to the meso‐to‐nanoscale.…”

“…[ 4,12 ] Further, infiltration of PSi with a number of nanomaterials has been carried out to take advantage of the peculiar properties of luminescent guest materials when confined within silicon‐based photonic structures with characteristic length down to the meso‐to‐nanoscale. [ 11,13,14 ]…”

Enhanced Biosensor Based on Assembled Porous Silicon Microcavities Using CdSe/ZnS Quantum Dots

“…PSi has been widely used in the field of biosensors [1], [2] due to its large specific surface area, good biological compatibility and absorbability, and low fluorescence background after solution treatment, such as DNA [3], [4], antigens and antibodies [5], [6], enzymes [7], [8] and other sensitive elements. PSi can be prepared into a variety of biosensors with monolayer [9], [10], Bragg [11], [12], microcavity [13], [14] and other structures. Compared with the Bragg structure, the microcavity (PSM) has the optical characteristics of half-height width and high transmittance at the resonance peak, so it has higher sensitivity [15].…”

4D Printing of Plasmon‐Encoded Tunable Polydimethylsiloxane Lenses for On‐Field Microscopy of Microbes

“…Nonethless, the cost of manufacturing of miniaturized optical components, i.e., the lenses and filters, for the assembling of add-on optical modules for smartphones with reduced size and weight (yet, hundreds of grams and of cm 3 ) has hampered the diffusion of smartphone-based microscopy to date. [5] To circumvent these limitations researchers have developed strategies to fabricate polymeric (e.g., polydimethylsiloxane, PDMS) magnifying lenses that can be directly attached to the smartphone camera to boost intrinsic magnification and resolution performance. [6][7][8] These strategies include hanging droplet of uncured PDMS deposited by inkjet printing on heated flat surface; [6] moldless thermal curing of PDMS droplet prepared using a moving needle extruder; [7] drop-casting of uncured PDMS droplet onto a smooth circular disk of poly(methyl methacrylate); [8] moldless printing of uncured PDMS droplet using nanostructured porous silicon (PSi) as templating layer.…”

“…[6][7][8] These strategies include hanging droplet of uncured PDMS deposited by inkjet printing on heated flat surface; [6] moldless thermal curing of PDMS droplet prepared using a moving needle extruder; [7] drop-casting of uncured PDMS droplet onto a smooth circular disk of poly(methyl methacrylate); [8] moldless printing of uncured PDMS droplet using nanostructured porous silicon (PSi) as templating layer. [5] In two cases the polymeric lens also embedded a rejection optical filter that enabled performing smartphone-based fluorescence microscopy leveraging image magnification and light rejection properties of the lens. [5,9] In Ref.…”